SEEING SAN JOSE SCALE AGAIN? - Dick Straub, Harvey Reissig, Peter Jentsch. Ed. Kevin Iungerman.

Reportedly, San Jose Scale is re-emerging in many NY orchards, and perhaps in some capital district operations.  Unlike mites, aphids, and other indirect pests, San Jose scale can seriously affect fruit quality itself, and like the other can cause poor tree health if unmanaged for a number of seasons. In extreme cases, SJS can lead to tree death. Both effective pesticides and several windows of treatment opportunity fortunately allow good control scenarios, of which the authors present several (see Table 1). And as they intone, and I repeat, “good coverage is necessary for control of scale.” K.

Treatment periods 1 and 2 (green-tip and half-inch green). Oil, Lorsban and Supracide directed against overwintered 'black caps' are long-time standards, and each still has a place in control programs.  Treatment during one of these time periods (both would probably be unnecessary) represents a first line of defense against scale. Recent work by Harvey Reissig and Dave Combs1 (Cornell NYSAES, Geneva) and historical evidence suggests that either oil or Lorsban alone perform as well as a traditional Oil + Lorsban tank-mix. The latter may have efficacy against overwintered OBLR larvae. (Esteem and Assail can also be used. Assail, has no phenology restriction; Esteem use is through Pink. (See next.)

 Treatment periods 3 and 4 (crawlers of the 1st and 2nd generations).  Three relatively new materials are on the scene: Provado, Esteem and Assail.  We have little NY experience with Provado against this pest; it may be worth a try if other susceptible insect species are present during recommended treatment periods.  Esteem, as an insect growth regulator juvenile hormone mimic, inhibits metamorphosis.  It is most effectively used at the first appearance of crawlers.  There is no contact toxicity and it tends to act very slowly.  Assail is a new-generation broad-spectrum neonicotinoid (see March Northeast Tree Fruit. K) that also is most effective when directed at the first appearance of crawlers. The efficacy of both materials is improved by the addition of oil but these tank-mixes may be phytotoxic and result in fruit finish problems. Both materials can also be used at half inch green.

Treatments for summer brood crawlers (similarly at the first appearance) are best timed by the use of a degree-day model (1st generation, 500 DD50; 2nd generation, 1451 DD50. (Each from 1 March).  Because each generation of crawlers is produced for extended periods of time, (as the SJS females do not lay eggs but give birth to live young, to gain complete control, a second application is advised 14 days later Real-time degree-day accumulations for specific cooperating New York NEWA sites can be found at  http://newa.nysaes.cornell.edu/base4504.htm Correct timing of treatments is critical with Esteem and Assail.  Calendar dates are generally too imprecise to be of benefit.

It's not too early to apply oil to smother overwintered Europen red mite eggs.  Use a 2% rate (= 2 gallons of oil for every 100 gallons water) for oil appliations up to half inch green, then decrease the amount of oil to 1.5% for applications up to tight cluster, and use only 1% from tight cluster to early pink.  Even a single oil applicatoin can prevent ERM problems for the rest of the season where pressure is light.  Two applications increases the odds for preventing the need for a summer rescue treatment.  Captan and oil should not be applied within 7-10 days of each other.  A 7-day separation should be adequate unless there is an absence of rain in the interim.